Process of preparing photographic prints



Patented Oct. 8, 1940 UNITED STATES PROCESS OF PREPARING PHOTOGRAPH? PRINTS .Oskar Siis, Wlesbaden-mebrich, Germany, assignor to Kalle a Go. Aktiengeeellschaft, Wiesbaden-Biebrlch, Germany No Drawing. ApplicaItliIon November 27, 1939, Se-

rial No. 306,343. 1938 23 Claims.

The present invention relates to a process of preparing photographic prints and to a lightsensitive material for carrying out said process.

In photographic diazo printing processes diazo compounds which are capable of coupling,

if desired together with azo components are generally used for the preparation of positive photographic prints. Moreover, the use of non-coupling light-sensitive diazo products 1. e. the socalled diazo sulfonates, is known. These compounds which more exactly must be designated as aryl-diazo-N-sulfonates are obtained by the reaction of aromatic diazonium compounds with sulfites, for instance sodium sulflte. With the aid of these diazo sulionates there are obtained,

according to the hitherto known processes, only negative copies from positive originals.

One object of the present invention is a process wherein the said diazo sulfonates are employed for the production of positive copies. Another object of the invention is a process for the production of positive copies which in contradistinction to the known diazotype processes hitherto used in practice involves the great advantage that the development can be carried through tern whereby at the parts exposed to light the diazo sulfonate is destroyed. The exposed material is developed by heating. A dyestufi is then formed at the places not struck by the light.

In the process according to the invention care must be taken that coupling diazo compounds produced as intermediate products on the decomposition of the diazo sulfonates by light have no opportunity of coupling with the azo com--' ponent present in the photographic printing material because this would lead to an undesirable discoloration of the ground of the prints obtained. This discoloration may be prevented by a suitable selection of the diazo sulfonates and a correct adiustment of the pH-value of the light-sensitive layer.

There are preferably used N-sulfonates of diazo compounds which possess only a relatively small coupling energy, for instance N-sulionates of diazo compounds coupling with phloroglucine only in an alkaline medium, but not in a neutral or an acid medium. It is also advantageous if the coupling diazo compounds from which the diazo sulfonates are derived show a high sensitiveness Germany December 5,

to light. There are, for instance, useful the diazo sulionates which are derived from paraamino-diazo compounds of the benzene series wherein either one hydrogen atom of the amino group or, and this being still better, both hydrogen atoms are substituted by alkyl groups. The alkyl groups may, for instance, be methylor ethyl-groups. Also propyland bntylgroups-the corresponding isomeric groups inclusively--come into consideration. One hydrogen atom may also be substituted by an aralkyl group of the benzene series, for instance a benzyl group. The N-sulfonates of para-dialkyl-aminobenzene-diazo compounds are, however, in general to be preferred. Those compounds have been found to be the most suitable which contain an alkoxy group, for instance a methoxy-, ethoxy-, propoxyor butoxy group in ortho-position to the diazo-sulfonate group.

As azo components there are particularly suitable readily coupling compounds, i. e. compounds of a high coupling energy. A criterion for the coupling power is, for instance, the behavior of the coupling components towards the diazo compound from 1-benzoylamino-2.5-diethoxv-4- aminobenzene. Such azo components asare capable of coupling with this diazo compound already in a neutral or even in an acid medium must be regarded as energetically coupling azo components. Phloroglucine, for instance, is very suitable. Resorcin is likewise useful. Good results are also obtained with acetoacetic acid anilide or other azo components which are derived from the following formula:

R.CO.CH:.CO.N

i CHa Similar useful aao components are mentioned in U. 8. Patent No. 2,150,565.

The light-sensitive layers used according to the invention may contain additional substances are somewhat modiiled thereby as regards their properties, such as sensitiveness to light and velocity of development. It is very advantageous to add a very weak acid, for instance boric' acid. to the layers, because the stability of the photographic printing material is increased thereby. Weakly acid salts, for instance primary sodium phosphate act in a similar manner as borlc acid. An addition of more strongly acid substances and an addition of substances having an alkaline reaction is not advisable because the stability of the layers is generally decreased by such additions. If desired, neutral salts of weak acids which are volatile in the heat, such as formic acid or acetic acid, may be added to the layers. For instance by the addition 01' zinc acetate or zinc formate to the layers the velocity of development is increased, this being probably due to the fact that on developing the photographic printing materials by the action of heat the salts mentioned split ofl. acid and yield oxides or basic compounds thus accelerating the development. It is advantageous to add to the light-sensitive material a small quantity of sodium bisulflte; this compound is for instance added to the sensitizing solution in -a quantity of about 0.2 per cent. The stability of the light-sensitive materials is improved in this manner.

After exposure to light the photographic printing materials described are heated to such an extent that av dyestufl is formed at the parts which have not been exposed to light. The extent of heating may readily be ascertained by tests. It is generally necessary to heat the material to a temperature considerably above 10 0., for instance to about C.-180 C. in order to attain a development within a sufllciently short time. Heating to a temperature considerably higher than that named above is not advisable because the paper, film or other sheet support would be impaired thereby. Heat may be supplied by the action of gases or vapors heated to more than 100 C., for instance air, steam or the like or by the action of correspondingly heated rollers, plates or the like.

The following examples serve to illustrate the invention, but they are not intended to limit it thereto:

(1) 1.1 grams of the sodium diazo-sulfonate from 1 diethy1amino-4-amino-3-ethoxybenzene, 1 gram of phloroglucine, .7 gram of thiourea,

.7 gram of thiosinamine and 1 gram of boric acid are dissolved in 50 cc. of water. A paper to which this solution has been applied is dried at about 70 C. After exposure to light under an original the paper is developed by bringing it in contact with a revolving roller heated to about C. Copies with dark violet-blue lines and a pure white ground are obtained.

Instead of the above-named diam-sulfonate there may be used diazo-sulionates from other l-dialkylamino-3-alkoxy-4-aminobenzenes, for instance from 1-dimethylamino-3-methoxy-4- aminobenzene, 1(N ethyl N propylaminc) -3- ethoxy-4-aminobenzene, 1(N-ethyl-N-butylamino) -3-ethoxy-4-aminobenzene, 1(N-ethyl-N-hydroxyethylaminM-B-ethoxyA-Kminobenaene or the like.

(2) 1.1 grams of the sodium diaao-sultonate from 1 diethylamino-li-amino-ii-methoxybenzene, 1 gram of 3-methyl-5-pyrazolone, .7 gram 5 of thiourea, .7 gram oi thiosinamine andlgram oi boric acid are dissolved in 50 cc. of water. With the aid of this solution there are obtained, analogous to Example 1, photographic prints having dark red lines.

If the acetoacetic acid anilide is used instead of 3-methyl-5-pyrazolone, photographic prints with yellow lines are obtained in a corresponding manner.

(3) 1.5 grams of the sodium N-sulfonate from l5 1 l-diethylaminc-3-ethoxy 4 diazobenzene are dissolved in 50 cc. 01' water together with '1 gram of phloroglucine, 1.5 grams of thiourea and 1 gram 0! boric acid. A paper which previously has been coated on one side with a solution of 29 10 per cent strength of zinc acetate is sensitized with this solution. The paper is dried at about 50 C.-60 C. and exposed to light under a pattern. The paper is then developed by the action 01' a current 01 air heated to about 140 C.- C. Positive copies having a pure white ground and dark blue lines are obtained. The diazo-sulfonate named may also carry a propoxy or a butoxy group instead 01' the ethoxy group.

1 Instead of the diazo-sulfonate named there may be used the diazo-sulfonate which is de- 1-mono-ethylamino-2-methyl-4- tained positive copies witiidark brown lines on a white ground.

Instead of the sodium diazo-sulionate, the corresponding potassium diazo-sultonate, ammonium diazo-sulfonate, zinc diaao-sulionate or other suitable salts may be used.

(5) 1.5 grams of the sodium diazo-sultonate from 1 (N ethyl-N-benzylamino) -4-aminobenzone, 1 gram of phloroglucine, 1.5. grams oi thicureaand 1 gramoi'boricacidaredisaolvedin 50 cc. of water.' The solution is applied to a paperpre-treated with a zinc-formate solution of 5 per cent strength to which K per cent cl ,5 copper nitrate has been added. The light-sensitive paper thus obtained is exposed to light under a pattern and then developed as described in Example 3.

Instead of the diazc-sulionate mentioned there may be used the diazo-sulfonate which is derived from 1 [N-ethyl-N- (2,6-dich1orobenzyl) amino] 4-aininobenzene.

I claim:

1. A process of preparing positive photographic prints with employment of non-coupling diazoproducts which comprises exposing to light imder a pattern a light-sensitive material consisting of a sheet support carrying a layer which latter comprises a light-sensitive diazo-sulionate and an azo component which material does not form a dyestufl on exposure to light and then developing the material by heating it.

2. A process according to claim 1 characterized inthat a diazo-sulfonate is used which is derived "2 from a diam-compound of a small coupling 3. A process of preparing positivephotographic prints which comprises exposing to light under a pattern a light-sensitive material consisting of a sheet support carrying a layer which latter comprises a light-sensitive para-amino-benzenediazo-sulfonate and an azo component which material does not form a dyestuif on exposure to light and then developing the material by heating- 4. A process according to claim 3 characterized in that the said diazo-sulfonate corresponds to the following general formula:

wherein R stands for a benzene nucleus which may carry a substituent, Z stands for a diazo-sulfonate group, X stands for alkyl and Y stands for a member of the group consisting of hydrogen, alnl or aralkyl of the benzene" series, Z being placed in para-position to the group 5. A process of the kind described which comprises exposing to light under a pattern a lightsensitive material consisting of a sheet support carrying a layer which latter comprises a diazosulfonate of the following general formula:

wherein R stands for a benzene nucleus which may carry a substituent selected from the group 'consisting of methyl, methoxy, ethoxy, propoxy and butoxy, Z stands for a diazo-sulfonate group, X stands for a member of the group consisting of methyl, ethyl, propyl and butyl and Y stands for a member of the group consisting of hydrogen, methyl, ethyl, propyl, butyl and benzyl, Z being placed in para-position to the group and an azo component and then developing the I material by heating it.

6. A process of the kind described which comprises exposing to light under a pattern a lightsensitive material consisting of a sheet support carrying a layer which latter comprises a diam- 'sulfonate of the following general formula:

wherein Z stands for a diazo-sulfonate group, V for a member of the group consisting of hydrogen and methyl, U for a member of the group consisting of methoxy, ethoxy, propoxy and butoxy, X for a memberof. the group consisting of methyl, ethyl, propyl and butyl and Y for a member of the group consisting of hydrogen,

methyl, ethyl, propyl, butyl and benzyl and an azo component and then developing the material by heating it.

7. A process of the kind described which comprises exposing to light under a pattern a lighta sensitive material consisting of a sheet support carrying a layer which latter comprises a lightsensitive diazo-sulfonate which is derived from a diazo compound of a small coupling energy and an'azo component of great coupling energy which material does not form a dyestuil' on exposure to light and then developing the material by heating it.

8. A process of the kind described which comprises exposing to light under a pattern a lightsensitive material consisting of a sheet support carrying a layer which latter comprises a lightsensitive para-amino benzene diazo suli'onate and an azo component of great coupling energy which material does not form a dyestui'f on exposure to light and then developing the material by heating it.

9. A process according to claim 8 characterized in that the said diazo-sulionate corresponds to the following general formula:

wherein R stands for a benzene nucleus which may carry a substituent selected from the group consisting of methyl, methoxy, ethoxy, propoxy and butoxy, Z stands for a diazo-sulfonate group, X stands for a member of the group consisting of methyl, ethyl, propyl and butyl and Y stands for a member of the group consisting of hydrogen, methyl, ethyl, propyl, butyl and benzyl, Z being placed in para-position to the group and then developing the material by heating it.

11. A process of the kind described which comprises exposing to light under a pattern a lightsensitive material consisting of a sheet support carrying a layer which latter comprises a dimsulfonate of the following general formula:

wherein Z stands for a diazo-sulfonate group, V for a member of the group consisting of hydrogen and methyl, U for a member of the group consisting of methoxy, ethoxy, propoxy and butoxy, X for a member of the group consisting of methyl, ethyl, propyl and butyl and Y for a member til , and an azo component of great coupling energy of the group consisting of hydrogen. methyl, ethyl, propyl, butyl and bensyl and an an component of great coupling energy and then developing the material by heating it.

12. A'process according to sum 1 wherein the light-sensitive layer is adjusted very weakly acid.

i3. A process according to claim 1 wherein the development is performed by heating the exposed material to a temperature above C.

14. A process according to claim 1 wherein the development is performed by heating the exposed material to a temperature of about to 180 C.

15. A process of the kind described which 'comprises exposing to light undera pattern a paper carrying a light-sensitive layer which latter comprises a l-diethyl-amino-3-ethoxy-4-bensene-diazo-sulfonate and phloroglucine and then develg oping the material by heating it to a temperature of about Mil-150 C.

I 16. A process of the kind described which comprises exposing to light under a pattern a paper carrying a light-sensitive layer which latter comprises a l-dimethyl-amino-3 methoxy 4 benzene-diazo-suli'onate and phloroglucine and then developing the material by heating it to a temperature 01' about -15 0 0.

17. A process 01' the kind described which oom- 1 prises exposing to light under a pattern a paper carrying alight-sensitive layer which latter comprises a l-diethyl-amino-i-benzene-diazo-suli'on-r ate and phloroglucine and then developing the material by heating it to a temperatureoi about 18. A light-sensitive material consisting of a sheet support carrying a diazo-sultonate correspondingto the following general formula:

Z-BN

Y- wherein It stands for a benzene nucleus which may carry a substituent, Z stands for a diam-sulionate group, X stands or alkyl andY stands for a member of the group consisting of hydrogen,

alwl or aralkyl of the benzene series, Z being placed in para-position to the group and an azo component of great coupling energy.

19. A light-sensitive "material consisting use sheet support carrying adiaao-sulionate ot the iollowing'general formula:

x z-' a-N wherein it stands for a nucleus which may carry a substituent selected from the group consisting of methyl, methoxy, ethoxy, propoxy and butoxy, Z stands for a diaso-suli'onate group, 2 stands for a member of the group consisting oi methyl, ethyl, propyl and butyl and Y stands for a member of the group consisting of hydrogen, methyl, ethyl, propyl, butyl and bensyl, ,2 being placed in para-position to the group andan azo component 01' great coupling energy;

20. A light-sensitive material consisting of a sheet support carrying a diazo-suiionate of the following general formula:

wherein Z stands for a diazo-s'uli'onate group, V for a member of the group consisting of hydrogen and methyl, U for a inember oi the group consisting of methoxy, ethoxy, propoxy and butoxy, X for a member of the group consisting of methyl, ethyl, propyl and butyl and Y for a member oi the group consisting oi hydrogen, methyl, ethyl, propyl, butyl'and benzyl and an azo component of great coupling energy.

21. A paper carrying a light-sensitive layer which lattercomprises a l-diethylamino-B-thoxy-i-benzene-diazo-sulionate and phloroglucine.

22. A paper carrying a light-sensitive layer which latter comprises a 1-dimethylamino-3- methoxy-i-benzene-diazo-suli'onate and phloroglucine.

23. A paper carrying a light-sensitive layer which latter comprises a l-diethylamino-4-ben-' zene-diazo-sulionate and phloroglucine.

m siis. 

